An organic electroluminescent device (hereinafter, referred to also as “light emitting device”) can be suitably used in applications such as display and illumination because of high light emission efficiency and low driving voltage, and is under active study and development. A light emitting layer can be formed by discharge type application methods typified by an inkjet printing method, by using a composition comprising a solvent and a soluble luminescent compound used for a light emitting layer of a light emitting device. By forming a light emitting layer using a discharge type application method, a large-area light emitting device can be produced by a simple process. For this reason, a composition comprising a soluble luminescent compound and a solvent is investigated.
Patent document 1 discloses that an isotropic light emitting layer can be formed by an inkjet printing method using a composition comprising a soluble luminescent compound and two or more kinds of solvents. The luminescent compound is a fluorescent compound. The difference in boiling point between the two or more kinds of solvents is about 50° C. to 55° C.
Patent document 2 discloses that a smooth light emitting layer can be formed by an inkjet printing method using a composition comprising a soluble luminescent compound and a solvent having a boiling point of 200° C. or higher. The luminescent compound is a fluorescent compound. A composition comprising a solvent having a boiling point of 200° C. or higher and a solvent having a boiling point of lower than 200° C. is not disclosed.